Health authorities stand by their call for pregnant women to get the swine flu jab as the total of number of reported miscarriages following vaccination increases to five.

The Centre for Health Protection said pregnant women were classified as a target group for the jab by the World Health Organisation and health authorities in the United States, Canada, Britain, Australia, Japan, Singapore and the mainland. 'The WHO recommends that, when human swine influenza vaccines become available, health authorities should consider making pregnant women a priority group for immunisation,' a centre spokesman said.

The centre yesterday confirmed it had received a report, the fifth of its kind, of a 39-year-old woman losing her baby on Thursday after getting the vaccine.

Local media reported the case on Monday. The woman, who had been pregnant for 12 weeks, received the vaccine on Christmas Eve.

Miscarriage occurs when a woman loses a baby when she is less than 24 weeks pregnant. If the baby dies later than that, it is called a stillbirth.

Figures released by the government on Monday cast doubt on its claim that the chance of a serious case of swine flu developing in pregnant patients who are infected is 10 times higher than for other people.

Of the 354 pregnant women tested with swine flu so far, only one was a serious case, representing a rate of 0.28 per cent. This compares with the 235 serious cases in 35,000 swine flu patients recorded in Hong Kong so far, a rate of 0.67 per cent.

'According to the WHO, infected pregnant women have a 10 times higher likelihood of requiring admission to an intensive care unit compared with the general population,' the centre said in a statement.

It said the US Centres for Disease Control and Prevention listed pregnant women as a priority group for the jab 'because they are at higher risk of complications and vaccination can potentially provide protection for infants who cannot be vaccinated'. About 290,000 pregnant woman in Europe had been vaccinated against swine flu, it said, citing a report by the European Medicines Agency.